A police officer needed hospital treatment after being bitten on the arm as she tried to stop a row.
The officer and a colleague had attempted to calm an “aggressive” confrontation between two women in Piccadilly Gardens, Manchester, on Saturday.
One offender “refused to let go” after the biting the policewoman, who had to “forcibly pull her arm” from her mouth.
The other woman “kicked out” when officers intervened, police said.
Both women, aged 40, were arrested on suspicion of assault of an emergency services worker and remain in custody.
Greater Manchester Police, which issued a graphic image of bite marks on the policewoman’s arm, said three of its officers were attacked over the weekend.
The other two officers were attacked when they stopped a break-in attempt in Stockport.
A 27-year-old suspect tried to avoid arrest by biting one officer and attempting to strangle the other, the force said.
He was Tasered and taken to hospital as a precaution before being arrested on suspicion of two counts of assault on an emergency worker.
Neither of the two police officers required hospital treatment.
Assistant Chief Constable Nick Bailey said the bite attack had been “particularly appalling”, and the officer had been badly bitten “simply for trying to defuse an altercation”
“It is saddening to have to reflect upon another weekend where our hard-working officers have been assaulted during the course of their duties,” he said.
“Thankfully, none of the officers involved suffered any lasting, serious injuries and I wish them well as they return to duty.”